Update `bytestring` submodule

this just pulls in the version bump to 0.10.6

bytestring @ fa7e1cc9

-Subproject commit cb85a5360bc540c88b3ae1886d07c741bec3cdaa
+Subproject commit fa7e1cc94982c0da85a022a501eadb1b347ea60c

testsuite/tests/safeHaskell/check/pkg01/ImpSafe03.stderr

 [2 of 2] Compiling Main             ( ImpSafe03.hs, ImpSafe03.o )
 
 <no location info>:
-    The package (bytestring-0.10.5.0) is required to be trusted but it isn't!
+    The package (bytestring-0.10.6.0) is required to be trusted but it isn't!